In the blog “Photo Editing Why” I referred to a number of types of photo editing. In this blog I hope to give you some insights into White Balance.
It’s probably obvious to a smart retired bloke like you, but something that was white at midday didn’t change colour through the day but it sure looked as if it did . At dawn it was more red then turned yellow and by midday it was a more blue. So they decided to use a mythical black box that was heated to different temperatures as the standard to describe whiteness of light. The black box would look red hot at around 3000 degrees. When you heated it up further at around 6000 degrees it got more blue. In fact the higher the temperature the bluer it got.
So today White Balance is the colour temperature that is present in the white parts of a photograph (described as warm or cold). Different areas of the photo can have different white balance but for general photography white balance refers to the photo as a whole since it was all most likely taken in the same light. For instance we might say that the photo looks very unnaturally yellow (warm) or blue (cold). It is sometimes difficult to tell whether an image has a ‘wrong’ white balance because the light at the time of taking the photo may have been just as it appears in the photo e.g. at sunset there is more yellow and red light. As you may have noticed, over recent years light globes often have the temperature of the light they produce printed on the side or on the box.
- Warm – 1000k to 4000k Candlelight, Sunrise/Sunset, Incandescent lamps
- Mid range – 4000k to 6500k Average Daylight, Electronic flash, “Daylight” fluorescent lights
- Cold – 6500k to 10000k Shade, Overcast Sky
So, an old light bulb was tungsten filament and it glowed at around 3200 degrees so if you had a white sheet of paper it would look slightly red in that light. On the other hand your TV is set to display a white screen at 6500 degrees which is the colour temperature of sunlight at midday. When you move into the shade, most of the light the falls on a sheet of white paper comes from the blue sky overhead and so it is bluer than the others. The problem is since we know it’s white, our eyes try to automatically correct for the colour of the light falling on it.
The simplest way to see whether the white balance is correct is to check whether the objects in a photo that you know where white in real life are represented as white in the photo.
Most cameras (and phones) do a pretty good job at automatically adjusting the white balance in a photo at the time it is taken however, film camera were set by the film, so all those slides you have stored in boxes will be all over the place. My digital camera overcorrects sunsets or dawn photos so some adjustment is usually required.
If you want to edit the white balance, most photo editing software can do that to some extent. If your image format is RAW you have more flexibility for editing than if the image is JPG format (see this Blog about RAW and JPG images). Photoshop and Apple Photos can automatically the white balance of neutral colours if you select the tool and click on a grey or white part of the photo.
The image on the left shows a few settings in the PhotoScape photo editing software that can allow you to adjust the white balance by directly adjusting the temperature or by setting the white balance using the option shown at the bottom.
As usual “Save as” when you save a photo and don’t overwrite your original. You can come back to the original and start again if you want a different result.
Click on the top or bottom images on the left to take a closer look.